Electrical transmission of images in natural colors



March 1, 1938. R. HARDING. JR 2,109,773

ELECTRICAL TRANSMISSION OF IMAGES IN NATURAL COLORS Filed Aug. 20, 1952 2 Sheet-Sheet 1 OUTPUT AMI? INPUT lNVENTOR RoaaR'r HARDING JR.

ATTORNEY March 1, 1938. R.- HARDING, JR

ELECTRICAL TRANSMISSION OF IMAGES IN NATURAL COLORS Filed Aug. 20, 1952 2 Sheets-Sheet 2 k ll INVENTOR ROBERT HARDING JR ATTORNEY Patented Mar. 1, 1938 UNITED STATES PATENT OFFICE ELECTRICAL TRANSMISSION OF IMAGES IN NATURAL COLORS Application August 20,

14 Claims.

This invention relates to the electrical transmission of images and has for its principal object the provision of an apparatus for reproducing the images in natural colors.

Another object of the invention is to produce a clearer image by eliminating dark lines which often appear in television images.

Other objects of the invention will be apparent as the description thereof proceeds.

One embodiment of the invention has been illustrated in the accompanying drawings, in which:

Fig. 1 is a diagrammatic perspective view, partly in section, of an apparatus embodying the invention;

Fig. 2 is a perspective view partly in section of a diagrammatic representation of the receiving apparatus;

Fig. 3 is a greatly enlarged perspective view I by the scanning apparatus similarly to the way a single image is scanned by the usual television scanning apparatus. A light sensitive cell receives light impulses from the scanning apparatus and translates them into electrical impulses which in turn, at the receiving end, are caused to modulate a light source, such as a neon glow lamp.

In front of the lamp is positioned another scanning device which, running in synchrony with the transmitting scanning device, reconstructs the plurality of images. Color screens color the images corresponding to the color values given to them at the transmitting end, and a suitable optical system, similar to the optical system in the transmitting apparatus is provided for projecting the images in superimposed relation upon a screen to form a single image. When the various parts of-the apparatus are properly arranged and properly operated, the image thrown upon the screen will appear in its natural colors.

In the patent to Cox No. 1,778,754 an optical system is shown for splitting up an object field into three separate images for making a photo- 1932, Serial No. 829,581

graphic record of the color value of an object. The same optical system as described in that patent may be used with the present invention although the invention is not intended to be limited to that particular optical system.

Referring now more specifically to the drawings an object It), shown for purposes of illustration to be an arrow, is illumined by a bright light II and an optical system I2 is positioned in such a manner as to project images of the arrow upon ascanning disc l3 rotatably mounted on a shaft l4 and rotated by a motor not shown in the drawings. The optical system comprises a compound positive lens l5 having a negative lens l6 and a positive lens ll placed in front of the negative lens and positioned therefrom at a distance depending upon the distance of the arrow from the lens and the relation between the focal lengths of the members.

A plurality of objectives l8, l9, and 20 may be positioned between the negative lens and the scanning disc l3. Any number of these objective lenses may be used but three is apparently all that is necessary as very natural color eifects may be obtained by using three images giving color values corresponding to the three primary colors. Thus the lens 18 may be provided with a' red color screen 2|, the lens l9 with a blueviolet color screen 22, and the lens 20 with a green color screen 23.

When the lenses are suitably positioned as clearly explained in the above mentioned patent three separate images 24, 25, and 26 with the different color values will appear on the scanning disc. Thus if the head 21 of the arrow shown enlarged in Fig. 3 is red, light from this portion will pass through the color screen 2| so that the head will appear on the image 24 but the rest of the arrow will be filtered out due to the different color thereof. It the tall 28 is blue-violet it will appear on the image 25 projected through the blue-violet screen 22, while if the center part 29 is green it will appear on the image 26 projected through the green color screen 23. In this manner diflerent colored portions of the ar-' row will appear in diflerent images and when light from these images passes through the scanning device and falls on the light sensitive cell impulses are produced corresponding to the amount of light in each image.

For this system it is preferable to use a light sensitive cell which is as nearly as possible equally responsive to light of different wave lengths, although this is not absolutely necessary as variations of responsiveness in the light sensitive cell to different wave lengths may be compensated for by adjusting the density of the color screens used. The impulses received by the light sensitive cell will, therefore, correspond to an area containing the three separate images.

For purposes of illustration a light sensitive.

cell 30 of the electrolytic type is shown, although any desired type of cell may be used as long as it will respond quickly enough to impulses received by the rapidly rotating scanning device. A suitable amplifier 3| is provided for magnifying the electrical impulses and such magnified impulses may be sent over the radio or through wires to the receiving set.

The receiving set may comprise a suitable amplifier 32 which would include, in the case of a radio, a radio frequency amplifier and detector, the output of which may be connected to a device for modulating a light source. In the present instance a neon glow lamp 33 comprising a pair of spaced apart plates is used, one of the plates being caused to glow over the entire surface thereof when current is run through the lamp. A receiving scanning disc 34 may be mounted on a shaft 35 so as to rotate close to the lamp 33 (preferably closer than is indicated in the drawings), the shaft being rotated by a synchronous motor (not shown) which will run in synchrony with the motor of the transmitting station provided the two are connected to the same power supply circuit, or may be caused to run at synchronous speed by any suitable synchronizing apparatus.

When the scanning devices of the transmitting and receiving stations are rotating in synchrony the triple image will appear in the plane of the receiving scanning disc if an observer looks through it toward the glow lamp, this being in accordance with principles now well known in connection with television. A second optical system 36 which may be similar to the optical system l2 may be mounted between a screen 31 and the scanning disc 34 in such a position as to project the image formed at the scanning disc upon the screen 31. The coplanar lenses 33 and 39 forming part of the optical system 36 are provided respectively with a red color screen 40 and a green color screen ll (the third lens and color screen being cut off by the section) thus the images 24', 25' and 26' on the plane of the scanning disc are colored'by their respective color screens so as to produce the arrow ill with its red head 21, its blue-violet tail 28, and its green center portion 29.

Inasmuch as accuracy of the image formed will depend largely on the color of the light used for producing the television signal a light having as white a discharge as possible is preferable, although the predominate color of the discharge, as for instance a neon reddish glow, may be compensated for by suitable adjustment of the color filters in the optical system.

Any type of scanning device may be used with the invention but I have illustrated scanning discs inasmuch as they are well understoodin the art at the present time and need no detailed description.

The optical system is shown as mounted in a sleeve so as to form one fixed unit and ordinarily such a construction will suffice as the focal distances may easily be predetermined in a television apparatus. It is to be understood, however, that adjusting devices may be provided to alter the spacing of the various lens elements. Also any of the lenses illustrated and described may consist of any number of elements and may be designed to compensate for any of the well known optical errors, such as coma, aberration, astigmatism, etc.

As the light impulses are picked up through a scanning disc at the transmitter by a light sensitive cell it will be necessary to illuminate the object suiilciently so that enough light reaches the cell to produce an impulse. Thus the lights H are used and are in no way limited as to number, type, or size.

It will thus be seen from the above that I have provided an apparatus whereby an object may be scanned by a transmitting device and reconstructed by a receiving device in the natural color of the object, this being accomplished by means of a single chain of impulses so that a single wave length may be used in radio in contra-distinction to the plurality of channels necessary in devices already proposed to accomplish th same purpose. The optical system used in connection with the transmitter and receiver is simple, easy to construct, and easy to adjust so that the apparatus is in reality no more complicated than the ordinary television transmittingand receiving apparatus.

An ordinary television apparatus, especially where a scanning disc is used for transmission and reception, has a tendency to produce an image having black horizontal lines across it caused by the space between successive holes in the scanning disc as they move across the image field; and this is more or less true with any scanning system. It will be noted in the present invention that inasmuch as three images are formed at the plane of the transmitting scanning apparatus the dark streak across each image will have to occur at exactly the same position for these streaks to appear on the finished image when the three images are superimposed at the receiving station on the screen. Inasmuch as it is practically impossible to cause these dark lines to fall at the same position on each image, due to the fact that each of the three images is scanned by different holes in the scanning disc, these dark lines will be completely balanced out when the three images are superimposed on the receiving screen. This is considered an important point as the lines formed across the image are objectionable and appear to be inherent with most scanning devices. While the primary object of the invention is to produce an image in natural colors it may be used, however, for the sole purpose of eliminating these dark lines, in which case the colored screens would be entirely omitted and the image would appear in black and white.

Many modifications of the invention may be resorted to without departing from the spirit thereof, and I do not, therefore, desire to limit myself to what has been shown and described except as such limitations occur in the appended claims.

What I desire to claim and secure by Letters Patent is:

1. In an apparatus of the class described means to simultaneously form a plurality of images of an object each having a different color value thereof, a single means to repeatedly scan the plurality of images, single means to translate the light impulses produced by said scanning means into electrical impulses, means at the receiving end to translate said electrical impulses into light impulses, means operated in synchrony with said first scanning means to repeatedly scan said light impulses, means to color the plurality of images formed at the plane of the scanning means similarly to the coloring of the light impulses from the corresponding images at the transmitting scanning means, and means to superimpose the plurality of images formed at the plane of the scanning means to form a single image.

2. In a device of the class described means to simultaneously form a plurality of images of an object field, means to give said images separate color values, single means to repeatedly scan said images, single means to translate the succession of light impulses produced by said scanning means into electrical impulses, means at the receiving end of the apparatus to translate said electrical impulses into light impulses, means to repeatedly scan the light impulses so produced, means to project the plurality of images formed at the scanning means upon a screen in superimposed relation, and means to color said images in correspondence to said first coloring means.

3. In a television transmitting set, optical means for condensing an object field, means to simultaneously form a plurality of images of the object field, means to give each of said images a different color value, means to repeatedly scan said colored images, and single means to translate the light impulses produced by said scanning means into electrical impulses.

4. In a television receiving apparatus, single means to translate the incoming television signal into modulated light, means to repeatedly scan a predetermined area of said light, means to project portions of the image formed at said scanning means in superimposed relation upon a screen, and means to give each portion so projected a different color value.

5. In an apparatus of the class described means to simultaneously form a plurality of images of an object field, means to give each image an independent color value, means to repeatedly break said images up into a plurality of successive electrical impulses, single means to translate said electrical impulses into light impulses, means to repeatedly rearrange said light impulses to form the original plurality of images, means to color each image corresponding to its equivalent original image, and means to superimpose said images to form a single image.

6. In a television transmitting device means to simultaneously form a plurality of images from an object field, means to give each of said images an independent color value, and single means to repeatedly break up said plurality of images into successive electrical impulses.

7. In a television receiving apparatus, single means to translate composite incoming electrical impulses into modulated light, means to repeatedly rearrange said light impulses to form an image, means to give portions of said image different color values, and means to superimpose said portions of said image to form a single composite image.

8. In .a device of the class described an object field, anoptical system positioned so as to form an image of said object field, a plurality of coplanar objectives included in said optical system for splitting the light rays so as to form a plurality of images of said object field, a color screen in the path of light rays passing through each of said coplanar objectives so as to give each of said images a different color value, and single means to repeatedly scan the images so formed.

9. In a device of the class described an object field, means to project said object field to form an image in space, means to split up said projected image into a plurality of separate similar images, means to give each of said images a diflerent color value, single means to repeatedly scan the plurality of images thus formed, and a light sensitive cell positioned so as to be influenced by said scanning means.

10. In a television receiving apparatus a lamp for producing modulated light, means to repeatedly scan the light so produced, a screen spaced from said scanning means, and an optical system between said screen and said scanning means, said optical system including a plurality of coplanar objectives adapted to superimpose the images of separate areas of said scanning device to form a single composite image on said screen.

11. In an apparatusof the class described an object field, an optical system positioned so as to receive light from said object field, said optical system comprising an objective, and a plurality of smaller coplanar objectives arranged so as to project into space a plurality of images of said object field, single means to repeatedly scan said projected images, single means to translate the succession of light impulses by said scanning means into electrical impulses, means at the receiving end of said apparatus to translate said electrical impulses into modulated light impulses, means to repeatedly scan said modulated light, said scanning means being driven in synchrony with said first mentioned scanning means, whereby said plurality of images will form on said second mentioned scanning means, a screen positioned from said scanning means, an optical system between said screen and said scanning means, said optical system comprising a plurality of coplanar objective and a single large objective so arranged that the plurality of images formed at the plane of said scanning means are superimposed upon said screen to form a single image, and means to impart a different color value to each of said images before superposition.

12. In an apparatus of the class described an object field, means to simultaneously project a plurality of images of said object field into space, single means to repeatedly scan said images, means to translate the light impulses produced by said scanning means into electrical impulses, means at the receiving end of said apparatus to translate the electrical impulses into modulated light impulses, means to repeatedly scan the modulated light impulses, a screen positioned from said second scanning means, and means to project portions of the image formed at said scanning means in superimposed relation upon said screen.

13. An apparatus of the class described comprising means to simultaneously form a plurality of complete images of a complete object field, the image of which is to be'transmitted, means to give each image an independent color value, means to repeatedly break said images up into a plurality of electrical impulses, single means to translate said electrical impulses into light impulses, means to repeatedly rearrange said light impulses to form the original plurality of complete images, means to color each image corresponding to its equivalent original image, and means to superimpose said images to form a complete image of the object field.

14. In an apparatus of the class described means to simultaneously form a plurality or complete images of a complete object field, the

rearrange saidiight impulses to form the original plurality of images, means to color each image corresponding to its equivalent original image and means to superimpose said images to form a single complete image of the complete object 5 field.

ROBERT HARDING, J R. 

